6.8 Tesla Horizontal Field Cryomagnet MA7

The horizontal high field cryomagnet has a restricted neutron access. There are 4 windows of 45 deg each, valid for a sample of 15 mm diameter. For larger samples, the opening angle for full access is sligthly smaller. In the field direction, the vertical access is +- 22.5, in fact, the access is a cone. Perpendicular to the field direction, the access is +-6.7 deg on a 15 mm sample, or 65 mm parallel access.

For access with polarized neutrons, an asymmetric mode (max. 6.2 Tesla) is available. This is needed when a beam perpendicular to the field is used.

This cryomagnet has strong stray fields due to the size of its coils. Before it may be used on any instrument, force tests have to be done. The specifications allow forces up to 1000 N vertically and 500 N horizontally.

MA7 Specifications

More information on intranet page (drawing): LdmWiki:MA7

MA7 Restrictions

Asymetric mode

For changing from symmetric mode to asymmetric mode and vice versa:

• on the top of the magnet under the aluminium cyclinder:
• make sure that the magnetic field is zero (IPS: shown current is 0 AND "persistent mode" LED is off)
• switch the magnet power supply IPS off
• open the cap using the screws marked on the picture above
• switch the cable from the SYM pin to ASY pin (or vice versa)
• the cable connected to the COM pin must always stay connected
• close the cap
• switch the magnet power supply on
• change the configuration of the IPS:
• press RAISE+LOWER+LOC/REM simultanously ("tESt" and "t 00" appears)
• press LOWER to go to "t 07", and then LOC/REM (""SUP" and "S 00" appears)
• press LOWER 5 times to go to "S 11" and then press LOC/REM (the induction value appears)
• press and hold LOC/REM and change the value with RAISE or LOWER, release LOC/REM when done
• press RAISE 7 times to go to "S 02" and then press LOC/REM (the value for max. current appears)
• press and hold LOC/REM and change the value with RAISE or LOWER, release LOC/REM when done
• press LOWER once to go to "S 01" and then press LOC/REM (the value for max. current appears)
• press LOC/REM again (the value for max. field appears)
• press and hold LOC/REM and change the value with RAISE or LOWER, release LOC/REM when done
• press LOWER once to go to "S 00" and then press LOC/REM ("tESt" and "t 00" appears)
• press LOC/REM again ("Stor.y" appears) and again